Precision machine vision inspection systems (or “vision systems” in short) can be used to obtain precise dimensional measurements of inspected objects. Such systems may include a computer, a camera and optical system, and a precision stage that is movable in multiple directions so as to allow the camera to scan the features of a workpiece that is being inspected. One exemplary prior art system that is commercially available is the QUICK VISION® series of PC-based vision systems and QVPAK® software available from Mitutoyo America Corporation (MAC), located in Aurora, Ill. The features and operation of the QUICK VISION® series of vision systems and the QVPAK® software are described in the QVPAK 3D CNC Vision Measuring Machine User's Guide, published January 2003, and the QVPAK 3D CNC Vision Measuring Machine Operation Guide, published September 1996, each of which is hereby incorporated by reference in their entirety. This product, as exemplified by the QV-302 Pro model, uses a microscope-type optical system to provide images of a workpiece at various magnifications, and moves the stage to traverse the workpiece surface beyond the limits of any single video image.
Measurement accuracy in the micron or sub-micron range may be desired in such systems. At such accuracy levels, even a slight FOV distortion due to optical system imperfections may lead to unacceptable measurement errors. The present invention is directed to providing a system and method for correcting the FOV distortion to a refined level in a precision machine vision inspection system.